Wattson in a good place ?!

Caustics gas isn't easy to avoid all the time, if you've taken cover in the open and he throws it you take damage and are slowed then forced to move into the open, and can easily get beamed, paired with a horizon ult, your in for a bad time.

Wattsons fences are easy to destroy if you block a door in most cases if a enemy opens the door they can easily get a line of sight to shoot them, caustic can block the door from being opened and if placed right and the doors opened the trap will set off straight away.

Wattsons fences you can spot from across the map, and if someone walks through them the damage is nothing compared to gas, also if Gibby throws his dome in the line of the fences It blocks them leaving a team free to push past them, making her fences useless, caustics gas destroys her fences to.

Yes he's big but he also takes less damage, wattson is smaller but takes more damage so if your half decent at hitting your shots it makes no difference.